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Thread: Just opened the pool... guess what I found?

  1. Back To Top    #1
    UnderWaterVanya's Avatar
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    Jun 2012
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    Mint Hill, NC
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    Just opened the pool... guess what I found?

    Algae!

    I "closed" the pool last fall using Polyquat per normal methods. The closing consisted of putting on the opaque safety cover and running the pump when too cold to avoid freezing. The cover is a little old and has some tiny holes (less than dime sized) in a few places and doesn't fit perfectly around the ladder (small gaps nothing more than 1/4-1/2 inch in size.

    Because of the cover and the polyquat I was hoping to open Algae free... . What I found was a light yellow green dusty mess all over. The Polaris 380 was left in the pool all season and the hoses were slimy and the unit was kinda spotted with algae.

    First step - measurements!

    Noon 4/14:
    FC: 0
    CC: 0
    CYA: > 0 < 20 (slightly cloudy after several minutes - could still see the dot with the tube all the way full; estimated < 10ppm)
    pH: 7.4
    TEMP: 65
    Water: Cloudy and greenish/yellow
    Pump PSI: 18
    Backwashed; PSI dropped to 14-15
    Nothing else measured; last year TA was around 70-80; CH was around 240.

    Added 3 bags of AquaChem dichlor shock left over from previous year. Used this to try to get some CYA in since I had none on hand. Did not realize that these were only 58% dichlor; the rest is likely a flocking/clarifier agent as the algae settled to the bottom in short order (by the next day). Originally I thought I was adding about 15ppm of FC and around 13ppm CYA. However now that I realize this was only ~ 28oz of dichlor the add was actually more like: FC +8.6; CYA: +7.8.


    3pm Measured again:
    FC: 4
    CC: 0.5
    Pump PSI: 22!
    Backwashed: PSI dropped to 13-14
    Water: Cloudy; still greenish; yellow but lighter

    Added 2 gallons of UNKNOWN % bleach (father-in-law purchased it!) assumed 5.25% as a guess.

    6pm measured again:
    FC: 8
    CC: 0
    Pump PSI: 13-14
    Water: still cloudy; not green at all
    Added another 2 gallons of the UNKNOWN % bleach - went home.


    CLOUDY DAY 4/15
    10am 4/15:
    Had Father-in-law add 2 gallons of the Unknown bleach.

    2pm 4/15:
    FC: 16.5
    CC: 0
    CYA: > 0 < 20 (measured on a cloudy day; seemed like it was harder to see the dot when full but still visible)
    Pump PSI: 13-14
    Temp: 65
    Water Crystal Clear NOT CLOUDY (yeah! progress) - algae dust on the floor still.

    No more bleach added since CYA added was less than originally anticipated. I am treating this as though the CYA was at most 20 for now.

    9am 4/16
    Overcast and Cloudy all morning
    FC: 14.0
    CC: 0.0
    Water: As previous; some algae on floor; water clear.
    Nothing added.

    Plan is to toss in more Dichlor (I have several pounds of 99%) as FC falls to 10-11; lack of sun is helping keep the FC high despite the lack of CYA.

    Goal is to get CYA up to 30 but slowly so shock is easier to reach and maintain. Treating this like Mustard Algae, once pool is clear clear clear then I will work on trying to remove light and ladder and clean these and toss things like cleaner in for 24 hours at MA shock levels.

    Did I miss anything?
    Inlaws Pool Boy since June 14th 2012, Pool built ~ 2003, In-Ground, 16'x32'
    13500 gal, Vinyl Liner, Fiberglass Slide, TF-100 Test Kit, Hayward 210T
    sand filter, A.O. Smith 1.5HP main pump motor (C48L2N134C1),
    Hayward SuperPump (model ?), Polaris 380 & PB4 Booster Pump

  2. Back To Top    #2
    JasonLion's Avatar
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    May 2007
    Location
    Silver Spring, MD
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    Re: Just opened the pool... guess what I found?

    Shocking is easier when CYA is around 30 than it is when CYA is lower. At lower CYA values, and chlorine isn't vanishing instantly, you lose more chlorine to sunlight than you do to cleaning up the pool.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

  3. Back To Top    #3
    UnderWaterVanya's Avatar
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    Jun 2012
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    Mint Hill, NC
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    Re: Just opened the pool... guess what I found?

    Quote Originally Posted by JasonLion
    Shocking is easier when CYA is around 30 than it is when CYA is lower. At lower CYA values, and chlorine isn't vanishing instantly, you lose more chlorine to sunlight than you do to cleaning up the pool.
    Good to know - thanks Jason!
    I'll toss some more Dichlor in and see if I can creep up on that target.
    It's been so cloudy it's been hard to verify what the numbers tell me I should be at on CYA but the sun is actually out for a change!
    Inlaws Pool Boy since June 14th 2012, Pool built ~ 2003, In-Ground, 16'x32'
    13500 gal, Vinyl Liner, Fiberglass Slide, TF-100 Test Kit, Hayward 210T
    sand filter, A.O. Smith 1.5HP main pump motor (C48L2N134C1),
    Hayward SuperPump (model ?), Polaris 380 & PB4 Booster Pump

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